Role of Endoscopic Ultrasonography in the Diagnosis and Management of Pancreatic Cystic Lesions

Pancreatic cystic lesions are commonly detected incidentally in up to 13.5% of cross-sectional imaging studies. Broadly, a distinction needs to be made between two main groups—mucinous and nonmucinous—as mucinous cysts predominantly have malignant potential. Among mucinous cysts, a further distinction is needed between high-malignant-risk potential lesions, which require surgical intervention, and low-risk lesions which are monitored with surveillance. Endoscopic ultrasonography (EUS) has emerged as a pivotal tool in distinguishing between these types and thus influencing patient management. EUS with or without fine-needle aspiration (FNA) provides high diagnostic accuracy in differentiating mucinous from nonmucinous cysts. A panel of biochemical tests can be performed on aspirated fluid, such as amylase, glucose, carcinoembryonic antigen, molecular testing, and cytological analysis. There is an emerging role of EUS-guided confocal endomicroscopy and artificial intelligence to improve the diagnostic accuracy of EUS. Beyond diagnosis, EUS also enables therapeutic interventions such as pseudocyst drainage and ablation of selected cystic neoplasms. This chapter discusses the role of EUS in the diagnosis, characterization, and management of pancreatic cystic lesions, highlighting its advantages, limitations, and potential future directions.